1. Field of the Invention
This invention relates to woodworking machines, more specifically woodworking machines for carrying out automatic working of wooden works based upon preformed digitizing data.
2. Description of the Prior Art
A plurality of woodworking machines for working works into desired three-dimensional form have been well known. In such woodworking machines, a model having a desired form is manually copied by means of a copying head, while at the same time a plurality of works are simultaneously worked into the same form as said model by means of a plurality of working heads driven in synchronous manner with said model copying head.
More recently, in place of these manual copying apparatuses, there have been developed and used various woodworking machines for automatically working on the basis of copying digitizing data compiled by CAD and the like.
As shown in FIG. 8 which shows a portion of said conventional woodworking machine, the edge portions of a work 1 are held respectively by a swiveling table 2 and a tailstock 3 located so as to oppose each other, these swiveling table 2 and tailstock 3 being shifted along a determined guide member in the axial direction (X direction) of said work. Further, a plurality of rotary jigs 4 driven by a not-shown driving apparatus are located in parallel relation to each other on one side surface of said swiveling table 2, whilst respective work-holders 5 for holding said work 1 against said jigs 4 while urging said work 1 towards said jigs 4 are located on the side surface of said tailstock 3 at the points corresponding respectively to said jigs 4. Further, respective cutting tools which can be shifted in the lateral direction (Y direction) and in the vertical direction (Z direction) are located above the positions corresponding to respective works 1 to be worked between said swiveling table 2 and said tailstock 3. And each of these cutting tools 6 has at its point a detachable cutting blade 7.
In such conventional woodworking machines, while said work 1 is rotatably driven by said jigs 4, said work 1 is shifted in X direction and at the same time said cutting tool 6 is shifted in Y direction and in Z direction on the basis of copying digitizing data memorized in a computer and the like, thereby to work said work 1 into a desired shape.
However, since said conventional woodworking machines show a predetermined and constant axis of rotation of said work 1 by means of jigs 4, the conventional type of machines have the disadvantage that, when the cutting shape in said work 1 is a cave having an overhang as shown in FIG.8, the cutting blade 7 of said cutting tool 6 can not reach the interior portion of the cave only through the sifts in X, Y, Z directions of said work 1 and said cutting tool 6 so that cutting of such cave can not be achieved.
For achieving this objective, it is advantageous to tilt the rotational axis of said jigs 4, but in the case of such a tilting axis of jigs 4, the rigidity around the axis of jigs 4 is considerably reduced with a complicated construction of device and with a higher manufacturing cost thereof.